I recently noticed a tweet from @CareersatBAT about how British American Tobacco South Africa had packed 200,000 meals of donated food for the Million Meal Challenge being run by Stop Hunger Now Southern Africa.

Careers at BAT is a twitter feed designed to profile staff working for one of the world’s largest tobacco companies, and the many attractions of working for the global transnational. Today it has nearly 6,000 followers.

But it is oddly silent on the impact of the company’s core business: promoting tobacco use, particularly in the stratospheric markets of impoverished nations where governments tend to have thin and poorly implemented tobacco control policies.

BAT has the third-largest share of the global tobacco market: 12% in 2013. The World Health Organisation puts the current annual global attributable tobacco death toll at 5.4 million, with one billion such deaths forecast for this century. So, 12% of a billion is 120 million deaths; 12% of 5.4 million is 648,000 deaths a year, or 74 every hour.

But tobacco doesn’t just kill its users directly. When you are dirt poor and cannot afford essentials, even smoking a few cigarettes a day can have widespread population health impacts. In 2001, researchers in Bangladesh detailed the impact on malnutrition of smoking by impoverished Bangladeshis.

Expenditure on tobacco, particularly cigarettes, represents a major burden for impoverished Bangladeshis. The poorest (household income of less than $24/month) are twice as likely to smoke as the wealthiest (household income of more than $118/month).

Average male cigarette smokers spend more than twice as much on cigarettes as per capita expenditure on clothing, housing, health and education combined. The typical poor smoker could easily add over 500 calories to the diet of one or two children with his or her daily tobacco expenditure.

An estimated 10.5 million people currently malnourished could have an adequate diet if money on tobacco were spent on food instead. The lives of 350 children could be saved each day.

When I saw the BAT tweet, I tweeted back:

I had two more interactions from the food charity before being blocked by both the charity and by @CareersatBAT.

Now, I am certain that not a single hungry southern African who ate one of the BAT packed food parcels would have refused to eat it had they known. All would have been extremely happy to have a meal that day. After all, the founder of the Salvation Army, William Booth argued that he would take money from the devil himself and wash it in the tears of the widows and orphans.

But that’s the thing with charitable activities. Supporting charities such as Stop Hunger Now in doing their life-saving, vital work provides inviolate “air cover” from criticism for companies wanting to distract public attention from their core business. The charity told me to butt out, just as high-profile sportspeople once regularly told health agencies they would be killing cricket, football and many other sports if they persisted in advocating for bans on tobacco sponsorship.

Tobacco companies such as BAT have publicised their donations to a wide variety of good causes, including tsunami relief and domestic violence prevention. In Australia, Phillip Morris donated to the Red Nose Day SIDS charity in 1999 even though environmental tobacco smoke is a risk factor for SIDS. In 2014, it spent £13.4m of its £13,971m revenue on its “corporate social investments” including charities. That represented 0.096% of its revenue, or one pound for every £1,043 earned.

Stop Hunger Now has an impressive array of corporate sponsors, and doubtless some will have some dubious reputations in some aspect of their business activities, environmental footprint or labour practices. Such considerations can invite a form of ethical nihilism with arguments about how there’s no such thing as clean money. But tobacco companies are utterly peerless when it comes to the death and misery leading up to those deaths that is the direct outcome of their business plans.

The people retweeting @CareersatBAT are proud they work for a company that saves lives. But at their annual performance reviews their key performance indicators are all inextricably tied to increasing the use of a product that will kill up to two in three of its long-term users.

There is no other industry which has a global, legally binding treaty focussed on driving it out of business, with 168 nations now having ratified the Framework Convention on Tobacco Control. It’s a given that all charities want to maximise their donations, but when it involves helping to ethically scrub clean tobacco companies’ net impact on society, it is important that an ethical audit extends to the those unintended effects.

In this editorial, written with Canadian colleague Stan Shatenstein, I explored the “ethics of the cash register” and why many universities now refuse to accept tobacco industry research support, again unique among all industries. The charity sector needs to go through the same examination of the ethics of inadvertently assisting tobacco companies to distract attention from its core business.